Digital cameras are well known. As their cost continues to drop, digital cameras grow in popularity. Digital cameras eliminate the need to have film developed. They also greatly reduce the need to have prints made, since digital pictures can be viewed on a computer monitor or the like. Although the initial cost may be higher, digital cameras have greatly reduced the overall cost of photography.
It has been estimated that about 100 billion photographs are taken each year world-wide. The use of digital cameras is expected to exceed the use of film cameras for the first time in 2004.
Digital cameras have widespread applications. Digital cameras can be used in amateur and professional photography. They can also be used in various industrial applications, such as machine vision.
With current digital photography resolutions exceeding 10 megapixels, the ability to capture the detail of a scene is incredibly good. Yet, existing photographs typically lack important information regarding the objects in an image. For example, typical contemporary photographs do not capture the three dimensional shape or size of object, because the image is recorded in a flat, two-dimensional fashion.
Contemporary three-dimensional cameras are known. However, state-of-the-art ranging systems based on complimentary metal oxide semiconductor (CMOS) imagers use time-of-flight (TOF) techniques to obtain depth information. According to this approach, a short pulse of light is sent to the scene to provide depth information. A very fast shutter is used in front of the CMOS imager to time the roundtrip distance to the different portions of the scene.
Since light travels at 300,000,000 meters/sec, a 1 millimeter change in scene distance corresponds to a mere 6 picoseconds in round trip time. As a result, time-of-flight techniques typically are limited to about 1 centimeter of resolution and 30 centimeters of measurement range.
In addition, due to the short time the shutter is open, time-of-flight techniques require a very bright light source. Of course, brighter light sources consume more power and cause concerns regarding eye safety.
In order to measure the short time delays, time-of-flight techniques further require the use of high-speed electronics that are expensive and consume a comparatively great amount of power. These factors make time-of-flight techniques expensive, bulky, and not well suited for the consumer camera market.
Thus, although such contemporary digital imaging systems have proven generally suitable for their intended purposes, they possess inherent deficiencies which detract from their overall effectiveness and desirability. Moreover, although the prior art has recognized, to a limited extent, the advantages of three dimensional imaging, the proposed solutions have, to date, been ineffective in providing a satisfactory remedy. Therefore, it is desirable to provide a three dimensional camera that uses improved techniques to obtain depth information regarding a scene being photographed.